Method of groove forming



Aug. 23, 1955 E, GROB ET AL 2,715,846

METHOD OF GROOVE FORMING Filed May 15, 1951 2 Sheets-Sheet l INVENTOR.

ERNST 6R BENJAMlHC-l B ATTORNEY Aug. 23, 1955 E. GROB ET AL METHOD OF GROOVE FORMING 2 Sheets-Sheet 2 Filed y 16, 1951 INVENTOR. Elm-451' 69.05 Beruamm Geog BY ATTORNEY United States Patent Ofiice Patented Aug. 23, 1955 METHOD OF GROOVE FORMING Ernst Grob, Zurich, Switzerland, and Benjamin Grob, Grafton, Wis., assignors, by mesne assignments, to Grub, Inc., Grafton, Wis., a corporation of Wisconsin Application May 16, 1951, Serial No. 226,572

2 Claims. (or. 8060) This invention relates to the art of metal rolling.

A general aim of the present invention is to provide a novel method of metal rolling particularly adapted for the rapid and economical production of gears and other similar repetitively grooved essentially cylindrical shapes.

A more specific object is to provide an improved rolling method for the purpose indicated in which each of the several grooves is progressively formed by the repetitive rolling engagement of a forming roller or succession of like rollers therewith.

Another object is to provide a gear forming method in which the gear teeth are formed by a metal rolling action that progresses across the face of the gear or substantially lengthwise of the axis thereof.

Other more specific objects and advantages will appear, expressed or implied, from the following description of a metal rolling method performed in accordance with this invention.

For purposes of illustration and explanation the method of the present invention is shown applied to the rolling of spur and helical gears, although it may be utilized to advantage in the rolling of splines and other shapes of the kind hereinabove mentioned.

In the accompanying drawings:

Figure l is a sectional view of gear rolling equipment capable of use in carrying out the method of the present invention. This view is taken substantially along the line 11 of Fig. 2.

Fig. 2 is a sectional view taken substantially along the line 2-2 of Fig. 1.

Fig. 3 is a fragmentary view similar to Fig. 2 showing a double acting roller arrangement.

Fig. 4 is a fragmentary view in plan illustrating an arrangement of parts for use in rolling helical gears.

In the metal rolling method herein illustrated a gear blank G is repeatedly operated upon by a rolling force herein exemplified by one or more forming rollers movable into and out of engagement with the blank. In this instance four such rollers are shown, each being journalled for free individual rotation within a suitable rotary carrier head 11. The head 11 is rigidly mounted for rotation about a fixed axis A, and is shown fixed to a supporting shaft 12 through which it is driven. It will of course be understood that the several rollers 10 are brought successively and repeatedly into forming engagement with the blank G by continuous rotation of the head 11, and that each is free to rotate about its individual axis while in engagement with the blank. The axis of rotation of each roller is parallel to the axis A of the carrier head 11 in the arrangement shown.

The blank G is shown releasably but securely fixed to a shaft 13 by which it is rigidly supported and by which it is rotated or indexed in timed relation with the rotary head 11. In this instance the blank is keyed to the reduced end 14 of the shaft 13, and clamped between an end shoulder on the shaft and a spacer sleeve 15, a nut 16 supplying the clamping pressure. In the arrangement shown in Figs. 1 and 2 the axis of rotation B of the blank is substantially at right angles to the axis of rotation A of the head 11.

During the rolling process the rate of rotation of the carrier head 11 is an exact multiple of the rate of rotation of the blank G. That is to say, during each complete revolution of the blank, the head 11 makes several complete revolutions, at least one for each of the several grooves to be formed on the blank. The head 11 is rotated continuously, and although the blank may be in termittently rotated and held stationary during engagement with each roller, the blank is preferably continuously rotated so as to utilize the higher operating speeds made available by continuous operation. Also during the rolling process the blank G is fed into and through the path of travel and zone of operation of the rollers 10 by advance of the shaft 13 along its axis.

The several rollers 10 are of substantially identical shape. In this instance each is shown equipped with a plurality of axially spaced, parallel, straight sided, peripheral ribs 17 and interposed grooves 18 whose combined cross-sectional contour corresponds essentially to that of a rack gear.

Each of the rollers 10 is axially fixed in the carrier head 11 with the projecting ribs 17 of each accurately positioned to reenter and properly mesh with the gashes, grooves, or tooth spaces previously formed in the blank G during the rolling process. For this purpose the ribs 17 of each roller are preferably disposed in planes ofiset from corresponding ribs of a preceding roller, the degree of offset being such as to compensate for the indexing rotation of the blank G.

From the foregoing it will of course be understood that, as a relatively slow axial feed movement is imparted to the blank G, the periphery thereof eventually enters into the paths of travel of the projecting roller ribs 17, which initially react thereon to produce a series of gashes g, hereinafter referred to as small increments of groove length, said gashes being spaced about the circumference of the blank, as shown, as a result of the indexing rotation thereof. Thereafter, as the feed and indexing of the blank G continues, these gashes are enlarged and deepened by the repeated rolling action of the successive rollers, as the ribs 17 thereof repeatedly enter and reenter the gashes and penetrate further into the blank. A penetration of maximum radial depth of course is attained when the leading face of the blank arrives at a dead center position immediately beneath the axis A of the carrier head 11. Thereafter, as the feed and indexing rotation of the blank continues, the repeated rolling action of the successive rollers progresses across the face of the blank until the several gashes are enlarged to form slots or grooves of uniform depth and of the desired length, and in this instance extending completely through the blank and conforming essentially to the tooth spaces of a conventional spur gear.

As previously indicated, indexing of the blank G may be effected by either intermittent or continuous rotation, but when the blank is continuously rotated, it is desirable, under some conditions of operation, that compensation be made for such rotation during engagement of the blank with the rollers 10. This is accomplished by a slight modification of the angular relation between the axis A of the head 11 and the axis B of the blank. More particularly, with the head 11 and blank G rotating in the directions indicated in Fig. 1, a slight angular displacement of the axis A in a direction to depress the right end thereof below the plane of the paper will induce each roller to travel tangentially with the rotating blank, as well as across the face of the blank, during its engagement with the blank. This correction angle is readily computed. In an arrangement in which the head 11 makes one complete revolution while the periphery of the blank is rotated through the distance of a single tooth pitch, then this correction angle is an angle whose sine is equal to the tooth pitch divided by the distance travelled by the roller .ribs 17 during onev complete revolution of the head 11.

Since this correction angle is rather small, and since the actual contact between each roller and blank is but momentary, this correction angle may seldom be used except in the production of high precision gears.

It will of course be understood that the above noted correction may be effected by adjusting either the axis A of the head 11 or the axis B of the blank G through the correction angle thus calculated. Also, under some conditions of operation, when such a correction angle is used, it is desirable to also angularly adjust the axes of the individual rollers, so that as each engages the blank G the ribs 17 thereof will lie in planes parallel to the grooves to be rolled.

It will also be understood that the above described process is applicable to the production of several gears in one operation, either by operating in the manner above described on a group of blanks clamped together in coaxial relation, or by operating in a similar manner on an axially'elongated blank and thereafter cutting or otherwise dividing the same into gears of desired face width. The arrangement of parts shown in Fig. 3 is particularly adapted for applying the method last suggested to an axially elongated blank of round bar form.

In the Fig. 3 arrangement the blank, in the form of a bar G, is fed lengthwise between two opposed rotary heads 11, each carrying a set of rollers of a kind and in the same manner as hereinabove described. In this instance the rollers 10 are so disposed as to engage and operate on opposite sides of the blank substantially simultaneously so that each radial thrust imposed on the blank G by each roller of one set is substantially counter-balanced by that imposed by a roller of the other set. It will of course be understood that, as the blank G is advanced lengthwise between the two sets of rollers 10, it is also rotated about its axis at a rate definitely related to the rate of rotation of the heads 11, in much the same manner and for the same purpose as the blank G previously described. This results in the formation on the bar G of a series of longitudinally extending grooves and intermediate ribs whose cross-sectional contour is essentially that of a conventional gear. Gears of desired face width may of course be obtained from the bar thus formed by merely cutting pieces of desired Width from the bar.

The metal rolling methods hereinabove described may be utilized in the production of helical as well as spur gears. In the production of helical gears the rollercarrying head 11 is angularly disposed relative to the blank G so that the angle between the axis B of the blank and plane of rotation of the rollers 10 is equal to the helix angle of the gear to be produced. With the parts thus arranged, the roller-carrier head 11 and the blank G are rotated in definite timed relation and the blank is also fed, preferably along its axis, in substantially the. same manner as previously described. However, when so fed an additional rotation is imparted to the blank. at a rate definitely related to the feed rate of the blank and such that the ribs 17 of the rollers will follow the helix angle of the gear.

It will of course be understood that the angular position of the roller-carrying head may also be modified in the manner hereinabove described to compensate for continued rotation of the blank.

Under some conditions of operation it may be advisable to feed the blank G of Fig. 4 in a direction parallel to the plane of rotation of the rollers 10, and thereby avoid the necessity of imparting the above described additional rotation to the blank.

Various changes may be made in any of the-rolling methods hereinabove specifically described without departing from or sacrificing the advantages of the invention as defined in the appended claims.

We claim:

1. The method of incremently rolling a series of elongated grooves extending lengthwise of a cylindrical surface and spaced around the circumference comprising, applying a rolling force into and out of penetrating rolling engagement with said surface to roll a small increment of groove length into said surface, coupled with rotation of said surface aboutits axis in such timed relation with repeated in and out applications of said rolling force to cause said rolling force to intermittently and succeedingly roll said surface at spaced intervals about its circumference to complete a series of grooves spaced around said circumference each of increment length, and feeding said surface axially to progress said incremental lengths into the length of the desired grooves.

2. The method of incremently rolling a series of elongated grooves extending lengthwise of a cylindrical surface and spaced around the circumference comprising, applying a rolling force into and out of penetrating rolling engagement with said surface, coupled with relative rotation of said surface and said rolling force about the axis of said surface in such timed relation with repeated in and out applications of said rolling force to cause said rolling force to intermittently and succeedingly roll said surface at spaced intervals about its circumference to complete a series of grooves spaced around said circumference each of increment length, and creating a relative feeding between said surface and said force axially of said surface to progress said incremental lengths into the length of the desired grooves.

References Cited in the file of this patent UNITED STATES PATENTS 

